Okay, helium balloons are light...but they"re not that light! The cool image listed below serves to make the suggest that helium is just one of the lightest elements. Helium belongs to a group of aspects called the noble gases.

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Figure (PageIndex1): Helium is among the lightest aspects in the periodic table.

What are Noble Gases?

Noble gases are nonreactive, nonmetallic facets in group 18 of the regular table. As you can see in the periodic table in the number below, noble gases encompass helium (left( ceHe ight)), neon (left( ceNe ight)), argon (left( ceAr ight)), krypton (left( ceKr ight)), xenon (left( ceXe ight)), and also radon (left( ceRn ight)). Every noble gases are colorless and odorless. They likewise have low boiling points, which explains why they room all gases in ~ room temperature. Radon, at the bottom that the group, is radioactive, so the constantly decays to various other elements.

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Figure (PageIndex2): Noble gases space in team 18 of the routine table, in this case the red column on the far right.

civicpride-kusatsu.netical nature of Noble Gases

Noble gases space the least reactive that all recognized elements. Your outer power levels space full since they each have actually eight valence electrons. The only exception is helium, which has just 2 electrons. Yet helium additionally has a full outer energy level, due to the fact that its only energy level (energy level 1) deserve to hold a maximum of two electrons. A full outer energy level is the most stable plan of electrons. As a result, noble gases cannot become an ext stable by reaction with various other elements and gaining or losing valence electrons. Therefore, noble gases space rarely affiliated in civicpride-kusatsu.netical reactions and virtually never kind compounds with various other elements.


Noble Gases and the Octet Rule

Because the noble gases space the the very least reactive of every elements, their eight valence electrons are offered as the conventional for non-reactivity, and also to describe how other facets interact. This is proclaimed as the octet ("group of eight") rule. According to this rule, atoms react to type compounds that permit them to have actually a team of eight valence electrons choose the noble gases. For example, salt (with one valence electron) reacts v chlorine (with 7 valence electrons) to kind the stable compound salt chloride (table salt). In this reaction, sodium donates an electron and also chlorine accepts it, offering each element an octet the valence electrons.


Some offers of Noble Gases

Have you ever before hadhelium balloons like those in the elephant image? uneven a balloon filled through air, a balloon filled with helium requirements to it is in weighted down so the it won"t to rise away—although girlfriend don"t need to use one elephant!

Early incandescent light bulbs, prefer the one pictured in the figure below, didn"t last very long. The filaments quickly burned out. Return air was pumped the end of the bulb, the wasn"t a complete vacuum. Oxygen in the little amount that air staying inside the light pear reacted v the metal filament. This corroded the filament and caused dark store on the glass. Filling a irradiate bulb v argon gas avoids these problems. That"s why modern light bulbs space filled v argon.

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Figure (PageIndex3): contemporary light bulbs are filled through the noble gas argon to stop corrosion that the filament inside.

Noble gases are also used to fill the glass pipe of lighted indicators like the one in the number below. Return noble gases space civicpride-kusatsu.netically nonreactive, your electrons deserve to be energized by sending out an electric existing through them. As soon as this happens, the electrons jump to a higher energy level. Once the electrons go back to their original power level, they provide off power as light. Various noble gases give off irradiate of various colors. Neon provides off a reddish-orange light, favor the native "Open" in the authorize below. Krypton offers off violet light and also xenon gives off blue light.

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Figure (PageIndex4): indicators like this one are filled v nobles gases like neon or xenon, which offer off light when energized.